Various types of high speed transistors are known in the prior art. A particular type of high speed transistor is known as a hot electron transistor. While early work on these devices focussed on low-temperature operation, because of small gain and small collector base barriers, advances in material technology have lead to operation of hot electron transistors at room temperature. An example of such a hot: electron transistor using materials lattice matched to GaSb are described in "Room-temperature operation of hot-electron transistors" by Levi et al., Appl. Phys. Lett., Vol. 51, pp. 984-986, and U.S. Pat. No. 4,829,343 entitled "Hot Electron Transistor" issued to Levi et al. May 9, 1989. Because these documents provide helpful background material, they are incorporated herein by reference. These devices rely upon a significant offset between an emitter injection energy and a collector energy barrier to allow for energy loss by hot electrons as they traverse the base and to reduce quantum mechanical reflection at the collector.
In previously known hot electron transistors, the hot electrons lose their energy by a variety of intravalley scattering processes including optical and acoustic phonon scattering, and various forms of plasmon scattering. Plasmon scattering is generally thought to be the most serious problem. Plasmons, which are the quantum particle manifestation of density waves in a concentration of majority carriers, feature a broad manifold of energy versus crystal momentum, expressed as k. Because of the broad plasmon energy manifold, hot electrons easily fulfill momentum, or k-vector, matching requirements and therefore lose energy rapidly in the form of plasmons. Once the hot electrons have lost more energy than a difference between their injection energy and the collector barrier, they contribute to an undesired base current rather than a desired collector current.
What is needed is a room temperature high speed transistor that does not suffer deleterious effects from plasmon scattering.